At Alpha Power, we know your generator is a lifeline—whether you’re powering your home, business, or farm. But did you know that real-world conditions like altitude, temperature, and humidity can all affect how efficiently your generator performs.

 

Here’s what you need to know to get the most out of your backup power—no matter where you live.

 

Why Generators Don’t Always Run at Full Capacity

 

Generators are typically rated to perform at Standard Temperature and Pressure (STP), which is close to sea level under moderate conditions. But we all know South Africa has anything but standard weather—and that matters more than you’d think.

 

When conditions shift—like in high-altitude areas, during heatwaves, or on humid summer days—your generator could be working harder and delivering less power than expected.

 

Altitude: Higher Up, Less Output

 

At higher altitudes (think Joburg or the Drakensberg), air is thinner—meaning there’s less oxygen available for combustion. This affects how well the engine runs and how easily it stays cool.

 

• Less oxygen = reduced combustion efficiency
• Cooler air = slower heat dissipation
• Result: Your generator can overheat or struggle to start

 

 

A diesel generator generally experiences a derating of 3% for every 300 meters above 1,000 meters elevation.

 

Temperature Extremes: Too Hot or Too Cold

 

• Hot Weather: Reduces air density, just like high altitude. That makes your engine work harder with less oxygen, increasing the risk of overheating.
• Cold Weather: Diesel fuel can gel in low temps, clogging filters and making it tough to start your generator.

 

Humidity: More Moisture, Less Power

 

High humidity replaces oxygen in the air with water vapor, which also disrupts the combustion process. The result? Reduced efficiency, harder starts, and more stress on your generator.

 

Sizing & Derating Your Generator

 

Most generators are built to run comfortably at around 75% of their total capacity for continuous use. In emergencies, they can handle 100%—but not for long stretches. And in tough conditions, you need to derate that output to avoid overload.

 

Typical derating guidelines:

Diesel or Petrol Generators: Reduce output by 2–3% for every 1,000 feet (308m) above sea level.

 

Maintenance Makes the Difference

 

Staying on top of servicing keeps your generator reliable for years to come. At Alpha Power, we recommend:

 

• Routine filter checks (especially in winter!)
• Monitoring temperature and fuel quality
• Making sure your generator is properly derated for your area
• Professional assessments for any performance issues

 

Power That Performs – Wherever You Are

 

Don’t get caught off guard. With the right setup and a little expert advice from us, your generator can keep running strong, even when conditions aren’t perfect. Whether you’re 2,000 meters up or bracing for another cold front, Alpha Power has your back.

 

Contact us to find the right backup power system for your needs.

 

Tel: 031 719 6000
Email: sales@alphapower.co.za